Laundry processing apparatus

ABSTRACT

The present invention relates to a laundry processing apparatus comprising: a tub for storing water and provided with an opening for putting in and taking out laundry; a drum, provided in the interior of the tub, for storing the laundry supplied through the opening; an agitator rotatably provided inside the drum; a rotating shaft connected to the agitator by penetrating the tub and drum; a driving part for rotating the rotating shaft; a connecting part provided with a connecting body fixed to the drum, and a body-penetrating hole which is provided so as to penetrate the connecting body and through which the rotating shaft is inserted; and a power transmission part moving back and forth inside the body-penetrating hole when the rotation shaft is rotating, and when same has rotated by a previously set number of times, transferring the power supplied by the rotating shaft to the connecting body.

TECHNICAL FIELD

The present invention relates to a laundry treatment apparatus.

BACKGROUND ART

In general, a laundry treatment apparatus is understood to include anapparatus adapted to wash laundry (objects to be washed or objects to bedried), an apparatus adapted to dry laundry, and an apparatus adapted toperform both washing and drying of laundry.

A laundry treatment apparatus of the related art includes a cabinet, adrawer retractably provided in the cabinet, and an accommodation unitdisposed in the drawer to provide a laundry accommodation unit (alaundry treatment space) for washing or drying laundry.

In the laundry treatment apparatus including a laundry accommodationunit that is disposed in a drawer retractably provided in a cabinet, inorder to improve the washing performance of the laundry treatmentapparatus, the volume of the laundry accommodation unit needs to beincreased so that the laundry accommodation unit can contain a largeramount of water and laundry.

Therefore, when designing a laundry treatment apparatus including alaundry accommodation unit disposed in a drawer, it is very important toimprove washing performance while minimizing the volume of the laundryaccommodation unit.

DISCLOSURE Technical Problem

An object of the present invention devised to solve the problem lies ina laundry treatment apparatus that is capable of improving washingperformance while minimizing the volume thereof.

Another object of the present invention devised to solve the problemlies in a laundry treatment apparatus in which a drum containing laundryand an agitator rotatably provided in the drum are rotated by a singledriving unit.

A further object of the present invention devised to solve the problemlies in a laundry treatment apparatus in which an agitator and a drumare rotated together in the same direction after the agitator hasrotated a predetermined number of times within the drum.

Technical Solution

The objects of the present invention can be achieved by providing alaundry treatment apparatus including a tub for containing water, thetub including an introduction port through which laundry is introducedinto or taken out of the tub, a drum provided in the tub, the drumcontaining the laundry supplied thereto through the introduction port,an agitator rotatably provided in the drum, a rotating shaft penetratingthe tub and the drum so as to be connected to the agitator, a drivingunit for rotating the rotating shaft, a connecting unit including aconnecting body secured to the drum and a body through-hole formedthrough the connecting body so as to allow the rotating shaft to beinserted thereinto, and a power transmission unit configured so as tomove reciprocatingly within the body through-hole when the rotatingshaft rotates, the power transmission unit transmitting the powerprovided by the rotating shaft to the connecting body after the rotatingshaft has rotated a predetermined number of times.

The power transmission unit may include a first stopper and a secondstopper secured to the body through-hole, the first stopper and thesecond stopper being spaced apart from each other by a predetermineddistance, an operating unit located in the body through-hole, theoperating unit being configured to move reciprocatingly between thefirst stopper and the second stopper, a through-hole formed through theoperating unit so as to allow the rotating shaft to be insertedthereinto, a first thread provided in the through-hole, and a secondthread provided at the rotating shaft so as to mesh with the firstthread, the second thread moving the operating unit toward the firststopper or the second stopper when the rotating shaft rotates.

The present invention may further include a receiving portion formed inthe connecting body, the receiving portion having a diameter that isgreater than the diameter of the body through-hole and defining a movingpath of the operating unit.

The present invention may further include an escape-preventing unit forpreventing the operating unit from escaping from the receiving portion,the escape-preventing unit being rotatably supported by the connectingbody and being configured to allow the rotating shaft to passtherethrough.

The first stopper may be an oilless bearing that is supported by theescape-preventing unit and is configured to allow the rotating shaft topass therethrough, and the second stopper may be an oilless bearing thatis supported by the stepped portion and is configured to allow therotating shaft to pass therethrough.

The first stopper may be a spring located between the escape-preventingunit and the operating unit so as to provide force to the operating unitso that the operating unit moves away from the escape-preventing unit,and the second stopper may be a spring located between the steppedportion and the operating unit so as to provide force to the operatingunit so that the operating unit moves away from the stepped portion.

The first stopper may be an escape-preventing unit for preventing theoperating unit from escaping from the receiving portion, theescape-preventing unit being rotatably supported by the connecting bodyand being configured to allow the rotating shaft to pass therethrough.

The second stopper may be a stepped portion formed between the receivingportion and the body through-hole.

The present invention may further include a cabinet including anentrance formed therein and a drawer to which the tub is secured, thedrawer being retractable from the cabinet through the entrance.

The rotating shaft may penetrate the lower surface of the tub and thelower surface of the drum, and may be secured to the agitator.

The rotating shaft may be arranged perpendicular to the ground on whichthe cabinet is seated.

The driving unit may include a stator secured to the lower surface ofthe tub while being located outside the tub, the stator being configuredto generate a rotating magnetic field, and a rotor configured to berotated by the rotating magnetic field generated by the stator, whereinthe rotating shaft may be secured to the rotor.

The agitator may include a body disposed in the drum so as to be securedto the rotating shaft, the body being formed in the shape of a circularplate, arranged parallel to the lower surface of the drum, and an armprotruding from the body toward the introduction port.

The present invention may further include a communication hole formedthrough the lower surface of the drum so that the inside of the drumcommunicates with the inside of the tub therethrough, and an agitatorthrough-hole formed through the body.

Advantageous Effects

The present invention may provide a laundry treatment apparatus that iscapable of improving washing performance while minimizing the volumethereof.

In addition, the present invention may provide a laundry treatmentapparatus in which a drum containing laundry and an agitator rotatablyprovided in the drum are rotated by a single driving unit.

In addition, the present invention may provide a laundry treatmentapparatus in which an agitator and a drum are rotated together in thesame direction after the agitator has rotated a predetermined number oftimes within the drum.

DESCRIPTION OF DRAWINGS

FIGS. 1 and 2 are views illustrating an example of a laundry treatmentapparatus according to the present invention.

FIG. 3 is a view illustrating an example of an agitator included in thelaundry treatment apparatus according to the present invention.

FIGS. 4 and 5 are views illustrating an example of a power transmissionunit included in the laundry treatment apparatus according to thepresent invention.

FIG. 6 is a view illustrating another example of the power transmissionunit included in the laundry treatment apparatus according to thepresent invention.

BEST MODE

Hereinafter, exemplary embodiments of the present invention will bedescribed in detail with reference to the accompanying drawings.Meanwhile, the configuration of an apparatus or a control methodthereof, which will be described below, is merely given to describe theembodiments of the present invention, and is not intended to limit thescope of the present invention. The same reference numerals usedthroughout the specification refer to the same constituent elements.

As shown in FIG. 1, a laundry treatment apparatus 100 according to thepresent invention includes a cabinet 1, a drawer 2, which is retractablyprovided in the cabinet 1, and a laundry accommodation unit 3 and 4,which is disposed in the drawer so as to provide a space required totreat laundry.

The cabinet 1 is provided with an entrance 11, through which the drawer2 may be drawn out of the cabinet 1 or may be inserted into the cabinet1. The cabinet 1 may be configured such that the length in the widthdirection (in the Y-axis direction) is greater than the length in theheight direction (in the Z-axis direction) (the drawer may be configuredsuch that the length in the width direction is greater than the lengthin the height direction).

As shown in FIG. 2, the drawer 2 includes a drawer body 21 having anopening formed in the upper surface thereof, and a drawer cover 25provided at the opening in the drawer body. That is, the drawer body 21may be configured to have a hollow hexahedral form, and the drawer cover25 may be secured to the drawer body 21 so as to define the uppersurface of the drawer body 21.

The drawer body 21 may be drawn out of the cabinet 1 or may be insertedinto the cabinet 1 using a slider. The slider may include a slider body271, which is secured to any one of the cabinet 1 and the drawer body21, and a slider housing 273, which is secured to the remaining one ofthe cabinet and the drawer body in order to define a moving path of theslider body 271.

The drawer body 21 is provided at the front surface thereof with adrawer panel 23, which serves as means for opening and closing theentrance 11 of the cabinet.

The drawer panel 23 may be provided with a control panel 231 (refer toFIG. 1) for controlling the operation of the laundry treatment apparatus100. The control panel 231 is provided with a unit (a controller of thelaundry treatment apparatus) for controlling units for supplying waterto the laundry accommodation unit 3 and 4 and discharging water from thelaundry accommodation unit 3 and 4 (a water supply unit and a waterdischarge unit), a unit for rotating laundry (a driving unit), units forsupplying steam or hot air to laundry (a hot air supply unit and amoisture supply unit), and the like.

In addition, the control panel 231 may be provided with an input unit,for enabling a user to input control commands into the laundry treatmentapparatus 100, and a display unit (a unit for displaying operationalinformation of the laundry treatment apparatus), for enabling a user tocheck control commands input through the input unit or notifying a userof the state of execution of the control commands input by the user.

The drawer cover 25 may be provided with a first cover through-hole 251and a second cover through-hole 253, which are formed through the drawercover 25 so that the inside of the drawer body 21 communicates with theoutside.

The laundry accommodation unit 3 and 4, which is provided in the drawer2, may include a tub 3, which is provided in the drawer body 21 so as todefine a space for containing water, and a drum 4, which is rotatablyprovided in the tub so as to contain laundry.

The tub 3 may include a tub body 31, which is secured to the inside ofthe drawer 2 by a tub support unit 311, and a tub cover 32, whichdefines the upper surface of the tub body.

The tub cover 32 is provided with an introduction port 33, through whichthe inside of the tub body 31 communicates with the outside of the tub.The introduction port 33 is opened and closed by a door 35.

The door 35 may be hinged to the tub cover 32 (so as to open and close aportion of the tub cover). The door 35 may be rotated toward the outsideof the drawer 2 through the first cover through-hole 251 formed in thedrawer cover 25. That is, the door 35 is located within a region of thetub cover 32 that corresponds to the first through-hole 251.Accordingly, a user may put laundry into the introduction port 33 byopening the door 35 after drawing the drawer 2 out of the cabinet 1.

The tub cover 32 is provided with a water supply hole 37, through whichwater is introduced into the tub body 31. The water supply hole 37 isconnected with one end of a water supply pipe 511, which will bedescribed later.

The drum 4 includes a cylindrical-shaped drum body 41 and communicationholes 411, through which the inside of the drum body communicates withthe tub. The communication holes 411 may be formed in thecircumferential surface and the lower surface 43 of the drum body 41.Accordingly, water contained in the tub body 31 may move into the drumbody 41 through the communication holes 411, and water in the drum body41 may move to the tub body 31 through the communication holes 411.

The drum body 41 is provided at the upper surface thereof with a drumintroduction port 42, through which laundry supplied through theintroduction port 33 is introduced into the drum body 41.

The reason why the laundry accommodation unit 3 and 4 is composed of thetub 3 and the drum 4 is to enable the laundry treatment apparatus 100according to the present invention to perform a washing function.Accordingly, in order to enable the laundry treatment apparatus 100 toalso perform a function of drying laundry in addition to the washingfunction, a hot air supply unit (not shown) for supplying hot air to thetub 3 may be further provided in the cabinet 1.

The hot air supply unit (not shown), which is provided in the laundrytreatment apparatus 100, may include a circulation duct, for circulatingthe air in the tub 3, and a heat exchanger, which is provided in thecirculation duct in order to dehumidify and heat the air discharged fromthe tub.

Alternatively, the hot air supply unit (not shown) provided in thelaundry treatment apparatus may include a discharge duct for dischargingthe air in the tub to the outside of the cabinet 1, a supply duct forsupplying the air outside the tub 3 to the tub 3, and a heat exchangerfor heating the air introduced into the supply duct.

When the laundry treatment apparatus 100 according to the presentinvention is constructed so as to perform a function of washing laundry,the laundry treatment apparatus 100 needs to further include a watersupply unit and a water discharge unit.

The water supply unit may include the water supply pipe 511, whichconnects a water supply source located outside the cabinet 1 to thewater supply hole 37, and a valve 513 for opening and closing the watersupply pipe 511 under the control of the controller (not shown).

The water supply pipe 511 penetrates the drawer cover 25 through thesecond cover through-hole 253. The water supply pipe 511 may beconfigured to have an extendable structure, or may be made of a flexiblematerial in consideration of the moving range of the drawer.

The water discharge unit serves to discharge the water contained in thetub 3 to the outside of the cabinet 1. The water discharge unit mayinclude a water discharge pipe 541 for guiding the water in the tub 3 tothe outside of the cabinet 1, and a pump 543, which is disposed in thewater discharge pipe 541 in order to discharge the water in the tub 3.The water discharge pipe may also be configured to have an extendablestructure, or may be made of a flexible material.

In order to minimize the volume of the laundry treatment apparatus 100having the above-described configuration, the volume of the laundryaccommodation unit 3 and 4 needs to be minimized. However, a reductionin the volume of the laundry accommodation unit 3 and 4 may reduce theamount of water that the tub 3 can contain, and thus may degrade washingperformance.

In order to solve this problem, the laundry treatment apparatus 100according to the present invention may further include an agitator 6,which is rotatably provided in the drum 4.

As shown in FIG. 3, the agitator 6 serves to agitate laundry supplied tothe drum body 41. The agitator 6 may include a body 61 disposed in thedrum and arms 63 protruding toward the drum introduction port 42 fromthe body 61.

The body 61 may be formed in the shape of a circular plate that isparallel to the lower surface 43 of the drum, and the arms 63 may bearranged radially about the rotation center of the body 61.

The body 61 is configured to rotate about a rotating shaft 67. As shownin FIG. 2, the rotating shaft 67 may penetrate the lower surface of thetub and the lower surface 43 of the drum, and may be secured to the body61. The rotating shaft 67 may be arranged perpendicular to the ground(perpendicular to the lower surface of the cabinet).

In this case, a rotating shaft bearing 39 may also be provided at thelower surface of the tub in order to rotatably support thecircumferential surface of the rotating shaft 67, and a drumthrough-hole 431, through which the rotating shaft is inserted, may alsobe formed in the lower surface 43 of the drum.

As shown in FIG. 3, the agitator 6 may further include agitatorthrough-holes 65, which are formed through the body 61. When the body 61of the agitator is configured as a plate that is parallel to the lowersurface 43 of the drum, the body 61 may interrupt the movement of waterthat is discharged to the tub 3 through the lower surface 43 of the drumor the movement of water that is introduced through the lower surface 43of the drum from the tub. This problem may be prevented by the agitatorthrough-holes 65.

The drum 4 and the agitator 6 having the above-described configurationsmay be rotated simultaneously in the same direction, or only theagitator 6 may be rotated by a driving unit 7, a connecting unit 8 and apower transmission unit 9.

In more detail, the driving unit 7, the connecting unit 8 and the powertransmission unit 9 are configured so that the agitator 6 and the drum 4are rotated simultaneously in the same direction after the agitator hasrotated a predetermined number of times.

As shown in FIG. 2, the driving unit 7 may include a stator 71, which issecured to the tub in order to generate a rotating magnetic field, and arotor 73, which is configured to be rotated by the rotating magneticfield generated by the stator.

The stator 71 is secured to the lower surface of the tub body 31 and islocated outside the tub body 31, and the rotating shaft 67 is secured tothe rotor 73.

Unlike the configuration illustrated in FIG. 2, the driving unit 7 mayinclude a driven pulley, which is secured to the rotating shaft 67 andis located outside the tub 3, a motor, which is secured to a locationoutside the tub 3, a driving pulley, which is configured to be rotatedby a rotating shaft of the motor, and a belt, which connects the drivingpulley to the driven pulley.

When the driving unit 7 is formed to have the configuration illustratedin FIG. 2, it may be possible to minimize power loss (improve washingperformance), which may occur during the power transmission process, incomparison with the mechanism in which the power from the motor istransmitted via the driving pulley, the driven pulley and the belt.

As shown in FIG. 4, the connecting unit 8 includes a connecting body 81,which is secured to the lower surface 43 of the drum, and a bodythrough-hole 85, which is formed through the connecting body 81 so as todefine a space into which the power transmission unit 9 is inserted.

The connecting body 81 serves to form the rotating shaft of the drum 4.The connecting body 81 may be provided at the circumferential surfacethereof with a coupling portion 83, which is secured to the lowersurface 43 of the drum.

The power transmission unit 9 is configured so as to movereciprocatingly within the body through-hole 85 when the rotating shaft67 rotates. The power transmission unit 9 is characterized in that ittransmits the power provided by the rotating shaft 67 to the connectingbody 81 after the rotating shaft 67 has rotated a predetermined numberof times.

The power transmission unit 9 may include an operating unit 91, whichmoves reciprocatingly within the body through-hole 85, a through-hole92, which is formed through the operating unit 91 and through which therotating shaft 67 is inserted, a first stopper 95 and a second stopper96 for setting a moving range of the operating unit 91, and a transferunit 93, which moves the operating unit 91 toward the first stopper orthe second stopper when the rotating shaft 67 rotates.

As shown in FIG. 5, the operating unit 91, which is formed in the shapeof a ring that is provided in the center thereof with the through-hole92, may be disposed in a receiving portion 87, which is formed in theconnecting body 81. The receiving portion 87 serves to define the movingpath of the operating unit 91. The receiving portion 87 may be formed soas to be concentric with the body through-hole 85 and to have a diameterlarger than that of the body through-hole 85.

The transfer unit 93 may include a first thread 931, which is providedin the through-hole 92, and a second thread 933, which is provided onthe circumferential surface of the rotating shaft 67 and meshes with thefirst thread 931 so as to move the operating unit 91 toward the firststopper 95 or the second stopper 96 when the rotating shaft 67 rotates.

In order to prevent the operating unit 91 from escaping from thereceiving portion 87, the connecting unit 8 may further include anescape-preventing unit 88, which is rotatably secured to the connectingbody 81 so as to prevent the operating unit 91 from escaping from thereceiving portion 87.

As shown in FIG. 4, the escape-preventing unit 88 has therein anescape-preventing through-hole 881 so as to allow the rotating shaft 67to penetrate the escape-preventing unit 88.

The escape-preventing unit 88 is rotatably supported by the connectingbody 81 via a bearing 89 disposed between the lower side of theescape-preventing unit 88 and the upper side of the connecting body 81.In this case, the escape-preventing unit 88 is kept in contact with thebearing 89 by a fastening member 883.

The fastening member 883 may be a nut, which is engaged with thecircumferential surface of the rotating shaft 67 and presses theescape-preventing unit 88 toward the bearing 89.

As shown in FIG. 5, when the operating unit 91 reaches the upper end ofthe receiving portion 87, the first stopper 95 serves to block themovement of the operating unit 91, thereby allowing the rotational forceof the rotating shaft 67 to be transmitted to the connecting body 81.

The first stopper 95 may be an oilless bearing, which is supported bythe escape-preventing unit 88. The oilless bearing is a device capableof minimizing frictional force between a moving object and a fixedobject without supplying a lubricant to a friction surface. The oillessbearing may be formed in the shape of a ring.

In the case in which the first stopper 95 is a ring-shaped oillessbearing and in which the rotating shaft 67 penetrates the center of theoilless bearing, the first stopper 95 may serve to transmit therotational force of the rotating shaft 67 to the connecting body 81, andmay also serve as a bearing to support the rotating shaft 67 so that therotating shaft 67 is rotatable within the connecting body 81.

When the operating unit 91 reaches the lower end of the receivingportion 87, the second stopper 96 serves to block the movement of theoperating unit 91, thereby allowing the rotational force of the rotatingshaft 67 to be transmitted to the connecting body 81. The second stopper96 may be a ring-shaped oilless bearing, which is supported by a steppedportion 871.

Alternatively, the first stopper 95 and the second stopper 96 may beformed to have the configurations illustrated in FIG. 6.

The first stopper 95 illustrated in FIG. 6 may be a spring that isdisposed between the escape-preventing unit 88 and the operating unit91, and the second stopper 96 may be a spring that is disposed betweenthe stepped portion 871 and the operating unit 91.

In this case, the first stopper 95 may be configured to provide force tothe operating unit 91 so that the operating unit 91 moves away from theescape-preventing unit 88, and the second stopper 96 may be configuredto provide force to the operating unit 91 so that the operating unit 91moves away from the stepped portion 871.

The above embodiments have been described as including the first stopper95 and the second stopper 96 in addition to the escape-preventing unit88 and the stepped portion 871, which may perform the function ofrestricting the movement of the operating unit 91. However, in the casein which the escape-preventing unit 88 and the stepped portion 871 areprovided, at least one of the first stopper or the second stopper may beomitted.

Hereinafter, the operation of the laundry treatment apparatus 100 havingthe above configuration will be described. Although, for convenience ofexplanation, FIG. 5 illustrates the state in which the operating unit 91is located in the middle of the receiving portion 87, a description willbe made hereinbelow of the state in which the initial position of theoperating unit 91 is a position at which the operating unit 91 is incontact with the second stopper 96.

When electric current forming a magnetic field for realizing clockwiserotation is supplied to the stator 71, the rotor 73 and the rotatingshaft 67 may be rotated in the clockwise direction.

When the rotating shaft 67 is rotated in the clockwise direction, theagitator 6, which is secured to the free end of the rotating shaft, maybe rotated in the clockwise direction within the drum 4.

When the rotating shaft 67 is rotated, the escape-preventing unit 88 mayalso be rotated therewith. However, since the escape-preventing unit 88is rotatably supported by the connecting body 81 via the bearing 89, thedrum 4, which is secured to the connecting body 81, is prevented frombeing rotated.

When the agitator 6 is rotated within the drum by the rotation of therotating shaft 67, the operating unit 91 is moved toward the firststopper 95 by the transfer unit 93. Accordingly, after the rotatingshaft 67 has rotated a predetermined number of times (a reference numberof times) (after the agitator has rotated a predetermined number oftimes), the operating unit 91 may come into contact with the firststopper 95.

When the operating unit 91 comes into contact with the first stopper 95,the rotating shaft 67 and the connecting body 81 are connected to eachother via the operating unit 91 and the first stopper 95, and thus theconnecting body 81 is rotated together with the rotating shaft 67.Accordingly, the drum 4 may be rotated together with the agitator 6 inthe same direction.

The reference number of times that only the agitator 6 rotates may bevariously set by appropriately configuring the transfer unit 93. Inconsideration of improvement of washing performance using the agitator,the reference number of times may be set such that the drum 4 is rotatedafter the agitator 6 has completely rotated at least once.

When electric current forming a magnetic field for realizingcounterclockwise rotation is supplied to the stator 71, both the rotorand the rotating shaft 67 may be rotated in the counterclockwisedirection.

In this case, the agitator 6 is rotated in the counterclockwisedirection within the drum by the counterclockwise rotation of therotating shaft 67, whereas the drum 4 is not rotated but remainsstationary until the operating unit 91 comes into contact with thesecond stopper 96.

Subsequently, when the operating unit 91 comes into contact with thesecond stopper 96 after the rotating shaft 67 has rotated apredetermined number of times, the drum 4 may be rotated together withthe agitator 6 in the counterclockwise direction.

Although the configurations or functions of the driving unit 7, theconnecting unit 8 and the power transmission unit 9 have been describedabove with reference to the configuration in which the tub is disposedin the drawer retractably provided in the cabinet, the driving unit, theconnecting unit and the power transmission unit may also be applied to alaundry treatment apparatus not including the drawer.

That is, the driving unit 7, the connecting unit 8 and the powertransmission unit 9 may also be applied to a laundry treatment apparatusincluding a cabinet, a tub secured to the inside of the cabinet, and adrum rotatably provided in the tub.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present inventionwithout departing from the spirit or scope of the invention. Thus, it isintended that the present invention cover the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

1. A laundry treatment apparatus comprising: a tub configured to receivewater, the tub defining an introduction port that allows introduction oflaundry into the tub and withdrawal of laundry from the tub; a drumlocated in the tub and configured to receive laundry through theintroduction port; an agitator located in the drum and configured torotate relative to the drum; a rotating shaft that penetrates the tuband the drum and that is configured to connect to the agitator throughthe tub and the drum; a driving unit configured to rotate the rotatingshaft; a connecting unit comprising a connecting body coupled to thedrum, the connecting body defining a body through-hole that extendsthrough the connecting body and that is configured to receive therotating shaft; and a power transmission unit that is configured to,based on rotation of the rotating shaft, move relative to the connectingbody within the body through-hole, and that is configured to, based onmovement of the power transmission unit within the body through-hole,selectively transmit power from the rotating shaft to the connectingbody in response to completion of rotation of the rotating shaft apredetermined number of times.
 2. The laundry treatment apparatusaccording to claim 1, wherein the power transmission unit comprises: afirst stopper and a second stopper that are coupled to the connectingbody, that are located in the body through-hole, that are spaced apartfrom each other; an operating unit that is located in the bodythrough-hole, that is configured to move between the first stopper andthe second stopper, and that defines a shaft through-hole configured toreceive the rotating shaft; a first thread defined in the shaftthrough-hole; and a second thread defined at the rotating shaft andconfigured to mesh with the first thread, the second thread configuredto, based on rotation of the rotating shaft, cause the operating unit tomove toward the first stopper or toward the second stopper.
 3. Thelaundry treatment apparatus according to claim 2, wherein the connectingbody defines a receiving portion that defines a moving path of theoperating unit, and wherein a diameter of the receiving portion isgreater than a diameter of the body through-hole.
 4. The laundrytreatment apparatus according to claim 3, further comprising a retentionunit that is configured to restrict the operating unit from moving outof the receiving portion, that is rotatably supported by the connectingbody, and that is configured to receive the rotating shaft.
 5. Thelaundry treatment apparatus according to claim 4, wherein the firststopper includes an oilless type bearing that is supported by theretention unit and that is configured to receive the rotating shaft,wherein the connecting body comprises a stepped portion located betweenthe receiving portion and the body through-hole, and wherein the secondstopper includes an oilless type bearing that is supported by thestepped portion and that is configured to receive the rotating shaft. 6.The laundry treatment apparatus according to claim 5, wherein the firststopper includes a spring that is located between the retention unit andthe operating unit and that is configured to provide force to theoperating unit to cause the operating unit to move away from theretention unit, and wherein the second stopper includes a spring that islocated between the stepped portion and the operating unit and that isconfigured to provide force to the operating unit to cause the operatingunit to move away from the stepped portion.
 7. The laundry treatmentapparatus according to claim 3, wherein the first stopper includes aretention unit that is configured to restrict the operating unit frommoving out of the receiving portion, that is rotatably supported by theconnecting body, and that is configured to receive the rotating shaft.8. The laundry treatment apparatus according to claim 3, wherein thesecond stopper includes a stepped portion located between the receivingportion and the body through-hole.
 9. The laundry treatment apparatusaccording to claim 1, further comprising: a cabinet that defines anentrance; and a drawer configured to receive the tub and configured toinsert into and retract from the cabinet through the entrance.
 10. Thelaundry treatment apparatus according to claim 9, wherein the rotatingshaft penetrates a lower surface of the tub and a lower surface of thedrum to couple to the agitator.
 11. The laundry treatment apparatusaccording to claim 10, wherein the rotating shaft extends in a directionperpendicular to a bottom surface of the cabinet is seated.
 12. Thelaundry treatment apparatus according to claim 10, wherein the drivingunit comprises: a stator located outside of the tub and coupled to thelower surface of the tub, the stator being configured to generate arotating magnetic field; and a rotor configured to rotate based on therotating magnetic field generated by the stator, and wherein therotating shaft is coupled to the rotor.
 13. The laundry treatmentapparatus according to claim 10, wherein the agitator comprises: a bodylocated in the drum and coupled to the rotating shaft, the body having acircular plate shape arranged parallel to the lower surface of the drum;and an arm that protrudes from the body toward the introduction port.14. The laundry treatment apparatus according to claim 13, wherein thelower surface of the drum defines a communication hole that enablescommunication between an inside of the drum and an inside of the tub,and wherein the agitator defines an agitator through-hole that extendsthrough the body.
 15. The laundry treatment apparatus according to claim2, wherein the first stopper and the second stopper are configured tolimit movement of the operating unit within the body through-hole, andwherein the power transmission unit is configured to, based on theoperating unit arriving at the first stopper or the second stopper,transmit power from the rotating shaft to the connecting body.
 16. Thelaundry treatment apparatus according to claim 2, wherein the firststopper and the second stopper are spaced apart from each other in alongitudinal direction of the rotating shaft.
 17. The laundry treatmentapparatus according to claim 4, further comprising a bearing that islocated between the connecting body and the retention unit, thatsurrounds an outer surface of the retention unit, and that faces thefirst stopper in a longitudinal direction of the rotating shaft.
 18. Thelaundry treatment apparatus according to claim 2, wherein an outerdiameter of the second thread defined at the rotating shaft is greaterthan an inner diameter of the first stopper.
 19. The laundry treatmentapparatus according to claim 3, wherein the rotating shaft comprises: afirst portion that defines the second thread and that is configured toinsert into the receiving portion; and a second portion that does notinclude a thread and that is configured to be positioned outside of thereceiving portion.
 20. The laundry treatment apparatus according toclaim 3, wherein the receiving portion and the body through-hole areconcentric and each extend in a longitudinal direction of the rotatingshaft.